Labeled Example Graph

Since insertions fill a buffer to the right and below point, the new
graph printing function should first print the Y or vertical axis,
then the body of the graph, and finally the X or horizontal axis.
This sequence lays out for us the contents of the function:

Indeed, with a little thought, we can easily come up with a variety of
vertical and horizontal labeling schemes. Our task could become
complicated. But complications breed confusion. Rather than permit
this, it is better choose a simple labeling scheme for our first
effort, and to modify or replace it later.

These considerations suggest the following outline for the
print-graph function: